Various techniques have been used to treat contaminated groundwater, such as liquid injection of chemical oxidants (e.g., in situ chemical oxidation (ISCO)). However, treatment of contaminated groundwater located in low permeable zones of aquifers, which can have various contaminants, like trichloroethene (TCE), can be difficult to accomplish using such conventional techniques. Slow-release oxidant candles have been developed and deployed to treat contamination in groundwater in such situations. For example, permanganate-paraffin candles have been developed for treating chlorinated solvents and persulfate-paraffin/iron-paraffin candles have been developed for treating petroleum contaminants.